Electrocardiography (ECG) signals acquired over hours or days can represent a large volume of data, difficult to present for review in a succinct way. Analysis of the data (detection and classification of individual heart beats and rhythms) allows advanced displays that can compact the presentation while emphasizing clinically significant features. Analysis, however, can take some time, delaying display of the data. Often machine analysis has errors that can exaggerate unimportant features of the data or hide important features. Some devices, like simplistic ambulatory recorders or transmitters, may have no processing capability to do an analysis, and yet could benefit from a longer duration data display. In some cases, a good data display can provide a method to input guidance to an analysis algorithm from a human operator before analysis begins.